The present invention relates to the substantially continuous cooking of food products and, in particular, to cooking under hydrostatic pressure of a liquid for improving cooking temperatures and cooking times.
Cooking of foods in a heated liquid typically requires the liquid within which the food is being cooked to combine with the food as well as provide a cooking temperature sufficient for completing the cooking process. By way of example, when cooking food products such as pasta, rice, legumes, or vegetables, large amounts of water are absorbed during the cooking process, with the weight of the cooked food generally increasing to 250% of the original dry weight for pasta, for instance. Further, it is known to cook food products within enclosed containers such as cans to provide for cooking under pressure developed within the can. However, the amount of liquid that can be absorbed by the food product is limited to that carried within the can. The cooked food contained within the can and the can are cooled, labeled, packaged, and prepared for delivery to a point of sale. However, while the cooking process may be enhanced by the pressure-style cooking within an enclosed can, it is not practical to remove the cooked food from the can for further preparation such as in a frozen entree. As a result, cooking within a can has typically only been used when no subsequent food preparation process is needed or desired.
Continuous cooking processes are known in the art. For example, Spiel et al. (U.S. Pat. No. 4,155,293 disclose cooking under atmospheric pressure in hot water to hydrate the food. Hickey (U.S. Pat. No. 3,614,924) teaches a conveyor and discharge chute for conveying a food product through a cooking bath comprising cooking fat. Williams (U.S. Pat. No. 4,582,047) discloses a high-humidity steam cooker including a continuously running conveyor for processing large volumes of food products passed through an energy-efficient steam cooker that preserves the product""s humidity, flavor, and appearance with water temperatures disclosed at essentially atmospheric pressures. Mette (U.S. Pat. No. 4,787,300) teaches an apparatus for continuously cooking and dehydrating foodstuffs, the apparatus including a multizone installation for preheating, boiling, and recooling through which the foodstuffs are passed. Larsen (U.S. Pat. No. 5,493,956) discloses a tank apparatus having movable rollers for receiving a pasta strand and routing the strand around rollers, including floatable rollers, for passing the pasta strand through the water bath to an exit conveyor. Depending on the blanching time required, movable rollers are repositioned to a desired elevation within the tank for blanching or cooking the pasta as it is transported through the water within the tank. D""Alterio et al. (U.S. Pat. No. 4,752,491) disclose the cooking of pasta ribbons on a zigzag conveyor passing through water carried within a tank.
It is an object of the present invention to provide an apparatus and method for cooking a foodstuff in a fluid cooking medium.
It is also an object to provide such an apparatus and method for reducing cooking time.
It is an additional object to provide such an apparatus and method that achieve a substantially continuous cooking process.
It is a further object to provide such an apparatus that has a smaller footprint than known previously in the art.
It is another object to provide such an apparatus and method that permit the absorption of cooking medium into the foodstuff.
An additional object is to provide such an apparatus and method that requires less cooking medium.
A further object is to provide such an apparatus and method that reduces a production of waste fluid.
Another object is to provide such an apparatus and method that reduces an amount of added xe2x80x9cmakeupxe2x80x9d cooking fluid and waste fluid.
It is yet an additional object is to provide such an apparatus and method that assist in reducing potential microbial contamination.
It is yet a further object to provide such an apparatus and method for improving a quality of the cooked foodstuff.
It is yet another object to provide an apparatus and method for sterilization.
These and other objects are achieved by the present invention, one aspect of which is a method for cooking food. The method comprises the steps of heating a liquid cooking medium in a cooking vessel. The vessel has an open top, a bottom, and a wall having a vertical height. The height is sufficient, and there is sufficient medium added, so as to attain a hydrostatic pressure in the cooking medium at a predetermined lower depth that is substantially greater than ambient atmospheric pressure.
The next step comprises downwardly conveying food to be cooked from an entry area at a surface of the cooking medium to the lower depth. The hydrostatic pressure thus facilitates a cooking of the food at a rate substantially greater than a rate at ambient pressure.
Another aspect of the present invention is for enhancing a food cooking process using increased hydrostatic pressure. The method comprises the steps of placing a predetermined quantity of food into a container and conveying the container on a pathway having a downward component through a heated cooking medium. The heated cooking medium has a sufficient depth so as to increase hydrostatic pressure along the column to at least about 1.25 atmospheres, that is, 0.25 atmospheres above ambient pressure at sea level. In order to obtain such a pressure level at sea level, for example, a pathway would comprise at least 4-5 feet downward.
Yet another aspect of the present invention is an apparatus for cooking food that comprises a cooking vessel as above. Means are also provided for heating the cooking medium and for downwardly conveying food to be cooked from an entry area along the predetermined level to the lower depth. As above, this is for permitting the hydrostatic pressure to facilitate cooking the food at a rate substantially greater than a rate at ambient pressure.
A further aspect of the present invention is a method for reducing wastewater output and makeup water usage by a cooking process for a food comprising a complex carbohydrate. This method comprises the steps of heating water in a cooking vessel as above and downwardly conveying the food to be cooked to the lower depth, also as above. This method further causes released complex carbohydrate from the cooking food to cause a lower viscosity increase than a viscosity increase at ambient pressure, thereby increasing a cooking effectiveness of the water and reducing a need for adding makeup water and disposing of wastewater. In addition, the more rapid cooking times of the present invention also decrease complex carbohydrate leaching from the food being cooked, again increasing cooking effectiveness and reducing a need for adding makeup water and wastewater disposal.